Good info, Thomas, thanks. I wasn't in a place where I could model the Sigma 18, so I couldn't be much help. I'm glad you could assist, your comments were very helpful.I'm working with some B&C woofers and mids, getting ready to offer more options. Looks like they'll work well in the Audiophile and Professional Series, and I might offer B&C tweeters as upgrade options on some of the other lines as well.